The Chevrolet copper-cooled engine was developed by Charles Kettering, the head of the Dayton Engineering Laboratories Company (Delco), GM's research wing in Dayton, Ohio. He started developing an air-cooled automobile engine in 1918.
Kettering chose to use vertical copper fins welded to the iron cylinders rather than cast iron fins, because copper's heat conductivity was 10-times better than iron. A big fan cooled the engine by drawing air up and over the cylinders.
Chevrolet was looking for something novel to compete with Ford's Model T, and began production of the Series M Copper-Cooled, with its 135 c.i., 20 h.p. air-cooled engine, in January 1923. However, there were many problems; by May, only 759 copper cooled Chevrolets had been built. About a third of these had to be scrapped, and of the remainder, 500 went to the sales organizations. Some 300 found their way to dealers, who sold about 100 to retail customers.
Because of the uneven air distribution, most of the engines would overheat badly, causing severe detonation (or pre-ignition) and loss of power. An embarassed Chevrolet ceased production, recalled all of the cars and destroyed them.Chevrolet would make no further attempts at air-cooling until 1960 with the Corvair.
Original air-cooled Chevrolets are extremely rare today, but one of the survivors is reported to reside in the Henry Ford Museum in Dearborn, Michigan.